Syringomyelia; myelin stain of spinal cord and medulla: Syringomyelia is a disorder in which cystic cavitation develops in the central portion of the spinal cord, most commonly within the cervical cord. The etiology and pathogenesis are unknown, but the disorder is considered to be basically developmental. The cyst enlarges with time and compresses and destroys the central commissures, often extending further into the lateral columns, posterior columns, and anterior horns, producing progressive neurologic impairment. Sometimes there is associated cavity formation in the medulla oblongata (syringobulbia). The cavity may be asymmetric in either the cord or the medulla.